This invention relates to an ultrasound diagnosis apparatus and a probe therefor. More specifically, this invention relates to an ultrasound apparatus utilizing a multi-plane ultrasound probe to be inserted into a body cavity, such as an esophagus, of a patient for obtaining ultrasound cross-sectional images along various angles.
As an example of an ultrasound probe of this type, there has been utilized a multi-plane TEE (transesophageal echocardiography) probe for being inserted transesophageally into an upper digestive tract, such as an esophagus or a stomach, of the patient and for obtaining cross-sectional images of a heart of the patient. Japanese laid-open (Kokai) patent 59-22534 discloses an ultrasound probe of this type. This probe comprises an array of ultrasound transducer elements on the end or side of a probe head and obtains cross-sectional images from the inside of the body cavity. The transducer elements are driven sequentially along one direction. The array can be rotated about an axis extending through the center of the array and perpendicular to its surface. This mechanism allows to obtain ultrasound cross-sectional images along various angles without moving the probe head in the body cavity. Imaging at any desirable angles is possible not being interfered by bones or subcutaneous fat layers.
The above-mentioned Japanese Kokai patent, U.S. Pat. No. 4,543,960 and European laid-open patent No. 509296 disclose unique mechanisms for rotation of the transducer array. The former two disclose wires to for rotation and the latter a shaft and a worm gear system.
As described above, the conventional multi-plane probe has a transducer array which is mechanically rotatable by manual operation to obtain cross-sectional images along various angles. However, the rotation wire may extend after a long use and this may cause inaccurate power transmission from an operation part to the array. Further, the wire operation for the rotation of the array may cause an undesired motion of an angle portion which varies a direction of the probe head. When the angle portion of the probe is bent, the power transmission by the wire may not be accurate because of the difference between the lengths of the inner and outer wires. Therefore, in the conventional multi-plane probe, the rotation angle may not be set accurately and the response of the rotation may not be sufficient. Generally, since the probe of this type is stuck to the inner wall of the esophagus and may cause pain to the patient, examination time is desired to be short and the poor response and inaccuracy is not favorable. Even in the shaft mechanism, developed to solve this problem, twisting of the shaft which is caused by low rigidity to keep flexibility may cause the same problems. In addition, backlash of the gear may cause the inaccuracy.
Furthermore, when rotating the array, the operator can not recognize what plane is being scanned. This also may cause a long and inaccurate examination.
The above-mentioned problems may occur not only in transesophageal probes but also in puncture, endorectum, endovaginal or intraoperative probes.